Hydroformylation Of Butenes

ABSTRACT

Mixed butene streams containing butene-1 and isobutylene and optionally butene-2 are hydroformylated under conditions that hydroformylates all the monomers to yield a mixture of valeraldehydes. Higher temperatures and/or longer residence times and/or higher partial pressure of carbon monoxide than in conventional processes are used to ensure hydroformylation of all the monomers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing of International PatentCooperation Treaty Application No. PCT/EP2004/010622 filed Sep. 17,2004, the disclosure of which is fully incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to saturated C5 aldehydes and theirderivatives and in particular C5 aldehydes that are produced by thehydroformylation of butenes. The invention further relates tounsaturated aldehydes that may be obtained from the aldol condensationof such aldehydes, saturated aldehydes and unsaturated and saturatedalcohols that may be obtained from hydrogenation of such unsaturatedaldehydes, and carboxylic acids that may be obtained from oxidation ofsuch saturated aldehydes. Furthermore the invention relates to thesubsequent reaction and derivatives of such products, primarily esters.

BACKGROUND

The invention is particularly concerned with products and theirderivatives obtained by the hydroformylation of C4 feeds comprising amixture of isobutylene and at least one normal butene, and optionallyother C4 components such as butane.

In this invention, the term butene or butylene generically refers to allhydrocarbon compounds having 4 carbons and at least one unsaturated bondthat bonds together two carbons. Examples of specific butenes include,but are not limited to, butene-1, butene-2 (which refers to thecombination of the cis and trans forms), isobutene or isobutylene, andbutadiene. Thus, the generic term butene or butylene refers to thecombination of all types of specific butene compounds.

Butene streams are used as raw materials for hydroformylation to producevaleraldehyde. In some commercial operations valeraldehyde is thendimerised and the product of dimerisation hydrogenated to produce 2propyl heptanol or mixtures thereof with other alcohols which arefinding use as alcohols in esterification reactions to produceplasticiser esters. Alternatively valeraldehyde may be hydrogenated toproduce pentanol or amyl alcohol or mixtures of different isomersthereof which may be used as a solvent or in the production of materialssuch as zinc dialkyl dithiophosphates. The valeraldehyde may also beoxidised to produce valeric acid or isomer mixtures thereof which may beused in synthetic ester lubricant production.

Butenes have generally been obtained from C₄ cuts that are obtained fromsteam cracking and catalytic cracking refinery processes. These cutstypically contain a mixture of C₄ saturated and unsaturated materialsincluding butadiene, normal butenes including both butene-1 andbutene-2, of which both the cis- and the trans-form typically occur, andisobutylene. The butadiene may be removed by extraction or reaction, orconverted by selective hydrogenation to produce a stream which containspredominantly normal butenes and isobutylene; such a stream is sometimesknown as raffinate-1. The composition of such a stream in terms of thedifferent hydrocarbon molecules may be determined by using conventionalgas chromatographic techniques.

More recently butene streams have become available from an olefin streamobtained from an oxygenate conversion reaction. Such a butene stream ischaracterized by having a high butene content, but is low in componentsthat can act as catalyst poisons. Although the butene componentsgenerally include a relatively high concentration of the moreundesirable butene-2 and isobutylene compounds, we have found that thestream can be hydroformylated to convert a significantly high portion ofthose components to aldehyde products, which may then be further reactedin the manner described above.

Oxygenates used as feed to, or formed during, the oxygenate conversionto olefins process, can be present in the butene stream. Such componentswill not significantly affect the hydroformylation process, norsignificantly affect the resulting aldehyde or aldehyde derivativeproducts.

In one embodiment of this invention, the butene stream used in theinvention is separated from an olefin stream that is obtained bycontacting oxygenate with an olefin forming catalyst. The oxygenatecomprises at least one organic compound containing at least one oxygenatom. Non-limiting examples include aliphatic alcohols, ethers, carbonylcompounds (aldehydes, ketones, carboxylic acids, carbonates, esters andthe like). When the oxygenate is an alcohol, the alcohol can include analiphatic moiety having from 1 to 10 carbon atoms, more preferably from1 to 4 carbon atoms. Representative alcohols include but are notnecessarily limited to lower straight and branched chain aliphaticalcohols and their unsaturated counterparts. Examples of suitableoxygenate compounds include, but are not limited to: methanol; ethanol;n-propanol; isopropanol; C₄-C₂₀ alcohols; methyl ethyl ether; dimethylether; diethyl ether; di-isopropyl ether; formaldehyde; dimethylcarbonate; dimethyl ketone; acetic acid; and mixtures thereof. Preferredoxygenate compounds are methanol, dimethyl ether, or a mixture thereof.

U.S. Pat. Nos. 6,770,791 and 6,784,330 describe how butene feeds for usein this invention may be obtained by the conversion of an oxygenate.

It may be desirable to increase the ethylene yield in the oxygenate toolefin process, since ethylene is typically of greater commercial valuethan other olefins produced in the process. One way of increasing theethylene yield in the oxygenate to olefin process is to operate theprocess such that there is less than 100% conversion of oxygenate toolefin product. This means that not all of the oxygenate feed will becompletely converted to olefin or some other final non-water product.Less than 100% conversion can also mean that some of the oxygenate feedis not converted, or that not all intermediate products are completelyconverted to olefin. For example, dimethyl ether can be used as a feedor it may form as an intermediate product in the conversion to olefin.Therefore, the presence of dimethyl ether in the olefin product willgenerally imply that the conversion of oxygenate to olefin is less than100%. By the same manner, other oxygenates, such as acetaldehyde, may bepresent, also indicating less than 100% conversion of feed orintermediate products.

In order to obtain the butene feeds from olefins produced fromoxygenates for use in this invention, it is desirable to separate abutene rich stream from the olefin product stream produced in theoxygenate to olefin process. Although it is preferred to obtain a butenerich stream that is low in oxygenate concentration, this inventionprovides the advantage that a high degree of separation of non-butenecompounds is not necessary. For example, propylene and pentene can berelatively easily removed from butene. Dimethyl ether, which may bepresent in the olefin product stream in rather large quantities at lessthan complete conversion, will tend to separate with the propylene richstream. Although some oxygenate contaminants, particularly acetaldehyde,are likely to be present in the separated butylene stream, little if anyoxygenate removal would be required to use the stream in furtherderivative processing if certain processes are used. According to thisinvention, it is desirable to use a rhodium hydroformylation catalystfor derivative processing of the separated butylene stream, becauselittle to no pretreatment of the butylene stream for oxygenate removalwould be required. Such catalyst is particularly suited to toleraterelatively high levels of acetaldehyde.

Separation can be accomplished using conventional means. Conventionaldistillation techniques are preferred.

It is known that within butene mixtures the different butene specieshave a different reactivity in hydroformylation reactions. For instancewhen using a rhodium catalyst in conjunction with a phosphine ligandsuch as triphenyl phosphine, butene-1 is considerably more reactive thanbutene-2 which has been more reactive than isobutylene. In addition itis known that the different pentanals produced by the hydroformylationof mixed butene feeds have different reactivities in subsequentaldolisation reactions with normal pentanal being considerably morereactive than 2-methyl butanal and accordingly various attempts havebeen made to keep the ratio of normal pentanal to 2-methyl butanal(sometimes known as the normal-to-iso ratio) as high as possible, suchas is described in U.S. Pat. No. 4,426,542. 3 methyl butanal which isproduced by the hydroformylation of isobutylene is however more reactivethan 2 methyl butanal in aldol reactions but is difficult to producefrom a butene mixture due to its lack of reactivity in rhodium catalysedhydroformylation.

During the hydroformylation of mixed butene feeds containing 1 buteneand cis- and trans-2-butene, these materials will convert to a mixtureof normal valeraldehyde and 2 methyl butyraldehyde. In order to enhancethe reactivity and usefulness of the aldehyde it is desirable toincrease the proportion of the normal valeraldehyde that is present, andwhen a rhodium catalyst is employed, this can be influenced by thechoice of the ligand used in conjunction with the rhodium.

Isobutylene or isobutene is not considered to be generally reactive inrhodium catalysed hydroformylation and has generally been removed priorto hydroformylation. However when subject to hydroformylation,isobutylene is known to produce 3 methyl butyraldehyde at lowconversion.

It is also known that mixed butene feeds containing isobutylene can behydroformylated (including the hydroformylation of the isobutylene) bythe use of a cobalt catalyst system. However such a system results inconsiderable isomerisation resulting in a high selectivity of normalbutenes to the less desired 2-methyl butanal, and in hydrogenationresulting in the formation of considerable amounts of C5 alcohols whichcannot then be used in subsequent aldolisation reactions.

U.S. Pat. No. 4,969,953 illustrates the hydroformylation of mixed butenefeeds containing isobutylene using a rhodium catalyst in conjunctionwith a triphenyl phosphine ligand and states that the reaction speed ofeach component of butenes is different. Examples 1 and 2 use a feedcontaining 4% isobutylene, Example 1 achieves a 26% conversion ofisobutylene resulting in a composition having a normal-to-iso ratio of10 and a ratio of 3 methyl butanal to 2 methyl butanal of only 0.2;Example 2 employs higher pressures and obtains a higher conversion ofboth isobutylene and butene-2 to produce a pentanal mixture in which theratio of 3 methyl butanal to 2 methyl butanal is again 0.2. Example 3employs a mixed butene feed containing 51.5% isobutylene at the lowerpressure and obtains a 2.3% conversion of isobutylene to produce apentanal mixture containing 3 methyl-butanal and 2 methyl-butanal in aratio of only 0.1.

U.S. Pat. No. 6,100,432 shows the separation of isobutylene fromraffinate-1, producing a raffinate-2, prior to hydroformylation with arhodium catalyst. U.S. Pat. No. 4,287,370 states that the C₄ feed tohydroformylation should contain no more than 1 wt % isobutylene.Similarly US Publication 2003/0022947 A1 discloses hydroformylation ofraffinate-2, an isobutene depleted stream said to contain no more than 5mol % isobutene. In this patent application, only the butene-1 ishydroformylated, the butene-2 and the isobutylene being substantiallyunreacted. An article by Walter J Scheidmeir of BASF in Chemiker-Zeitung96 Jahrgang (1972) Nr 7. pp 383-387 shows the hydroformylation of abutene stream containing significant amounts of isobutylene (i.e. 46%)in which most of the unsaturated materials including the isobutylene,are converted. In this case, it is clear that cobalt salts were used asthe hydroformylation catalyst, as evidenced by the high selectivity toalcohols in the product composition as well as the high yield ofdimethylpropanal and dimethylpropanol that are reported, a combinationof features that is typical for a high pressure cobalt based catalystsystem, and atypical for the low pressure rhodium and phosphorusliganded catalyst systems. The product mix, excluding heavies, wasreported to contain as much as 39.6%, presumably by weight, of variousC₅ alcohol isomers, and respectively 1.2% and 4.1% of dimethylpropanaland dimethylpropanol. U.S. Pat. No. 6,555,716 describes a process inwhich raffinate-1 is fed to a hydroformylation reactor that employs arhodium catalyst with a two phase aqueous system using a water solubleligand, i.e. trisulphonated triphenylphosphine. However, far from allthe isobutylene is converted, the highest conversion of isobutylenebeing 13.6% in Example 13. Furthermore the yield in this reaction is lowand high catalyst recycle volumes are required, giving the process asdescribed a low effectivity and a low efficiency.

SUMMARY

We have now found that C4 feeds, i.e. mixed butene feeds containingnormal butene(s) and isobutylene may be hydroformylated to produce newC5 aldehyde mixtures with a high ratio of normal valeraldehyde to 2methyl butyraldehyde and an increased ratio of 3 methyl butyraldehyde to2 methyl butyraldehyde.

We have also found that the ratio of 3 methyl butanal to 2 methylbutanal may be increased by increasing the extent of hydroformylation ofisobutylene in C4 (mixed butene) feeds and that a more reactive aldehydemixture may be obtained. In addition the reactivity of the mixedvaleraldehyde material may be increased by employing conditions thatfavour the conversion of cis- and trans-2 butene to normalvaleraldehyde. This has the combined benefits that there is no need forisobutylene removal from conventional mixed butene feeds prior tohydroformylation and a more reactive C5 aldehyde mixture is obtained.Furthermore the more reactive C5 aldehyde mixture and its derivativesare novel and useful chemical compositions.

Accordingly the present invention provides a C5 aldehyde mixturecomprising n-pentanal, 3-methyl-butanal and 2-methyl-butanal wherein

i. the ratio of n-pentanal to 2-methyl-butanal is from 3:1 to 100:1 and

ii. the ratio of 3-methyl-butanal to 2-methyl-butanal is at least 0.3:1.

In such C5 aldehyde mixture the ratio of 3-methyl-butanal to2-methyl-butanal is preferably at least 0.5:1, more preferably at least1:1, yet more preferably at least 10:1 and most preferably at least20:1. For example the ratio is preferably in the range 0:3:1-30:1, morepreferably 0.5:1-25:1 and most preferably 1:1-20:1. The ratio ofn-pentanal to 2-methyl-butanal is preferably in the range 5:1-50:1, morepreferably 8:1-40:1, yet more preferably 10:1-35:1 such as 15:1-35:1,and most preferably 20:1-30:1.

In a further embodiment the invention provides a process for theproduction of an aldehyde mixture comprising hydroformylating a C4 feedcontaining one or more normal butenes and from 15 wt % to 50 wt %isobutylene in a single liquid phase in the presence of a catalystcomprising a rhodium complex in conjunction with an organophosphorusligand (preferably comprising a tertiary organophosphine or anorganophosphite) and under conditions that convert normal butenes andconverts at least 15% of the isobutylene to produce a mixture of isomersof valeraldehyde.

In a yet further embodiment the invention provides a process for theproduction of an aldehyde mixture comprising hydroformylating a C4 feedcontaining one or more normal butenes and from 2 wt % to 50 wt %isobutylene in a single liquid phase in the presence of a catalystcomprising a rhodium complex in conjunction with an organophosphorusligand comprising an organophosphite and under conditions that convertnormal butenes and convert at least 15% of the isobutylene to produce amixture of isomers of valeraldehyde.

In both process embodiments we prefer that at least 20% or 30%, morepreferably at least 45%, even more preferably at least 55%, and mostpreferably at least 60% of the isobutylene is converted.

The invention also provides for aldehyde products containing mixtures ofvarious valeraldehydes. In one embodiment, there is provided an aldehydemixture comprising at least 85 wt % n-valeraldehyde, based on totalamount of aldehydes in the mixture. Preferably, the aldehyde mixturecomprises at least 88 wt % n-valeraldehyde, more preferably at least 90wt % n-valeraldehyde, and most preferably at least 92 wt %n-valeraldehyde, based on total amount of aldehydes in the mixture.

The mixture will generally include a limited quantity of3-methylbutanal. In one embodiment, the mixture is comprised of notgreater than 8 wt % 3-methylbutanal, based on total amount of aldehydesin the mixture. Preferably, the mixture is comprised of not greater than6 wt % 3-methylbutanal, more preferably not greater than 5 wt %3-methylbutanal, and most preferably not greater than 4 wt %3-methylbutanal, based on total amount of aldehydes in the mixture.

Although the amount of 3-methylbutanal in the aldehyde mixture isrelatively low, there will generally be at least an easily measurableamount present. In one embodiment, the mixture is comprised of at least1 wt % 3-methylbutanal, based on total amount of aldehydes in themixture. In another embodiment, the mixture is comprised of at least 2wt % 3-methylbutanal, or at least 3 wt % 3-methylbutanal, based on totalamount of aldehydes in the mixture.

The mixture will also generally include a limited amount of2-methylbutanal. In one embodiment, the mixture is comprised of notgreater than 7 wt % 2-methylbutanal, based on total amount of aldehydesin the mixture. Preferably, the mixture is comprised of not greater than6 wt % 2-methylbutanal, more preferably not greater than 5 wt %2-methylbutanal, and most preferably not greater than 2 wt %3-methylbutanal, based on total amount of aldehydes in the mixture.

Although the amount of 2-methylbutanal in the aldehyde mixture is alsorelatively low, there will generally be at least an easily measurableamount present. In one embodiment, the mixture is comprised of at least0.05 wt % 2-methylbutanal, based on total amount of aldehydes in themixture. In another embodiment, the mixture is comprised of at least 0.1wt % 2-methylbutanal, based on total amount of aldehydes in the mixture.

The C4 feed, ie butene stream, used in the process of this invention maybe obtained from the cracking of hydrocarbon gases, condensates orpetroleum feedstocks or from oxygenate conversion. The stream preferablycontains at least about 60 wt % butenes, based on total weight of thestream. Streams more concentrated in butene compounds are still moredesirable. For example, butene streams containing at least about 70 wt%, 80 wt %, and 90 wt % total butenes, based on total weight of thebutene stream, are progressively more desirable.

Of the total amount of butenes present in the butene feed stream, thereis desirably a significant concentration of butene-1. However, when thebutene feed streams are predominantly recovered from olefin productstreams of oxygenate conversion reactions, such streams may include asignificant amount of butene-2, and to a lesser extent, a significantamount of isobutene. Although butene-1 is more readily converted toaldehyde via hydroformylation reactions, this invention provides forsignificant conversion of butene-2, as well as isobutene, to aldehydevia hydroformylation.

In one embodiment, of the total amount of butenes present in the butenefeed stream, at least 10 wt % of the total butene concentration isbutene-1. Preferably at least 15 wt %, and more preferably 20 wt %,based on total weight of butene present in the stream, is butene-1. Theconcentration of butene-1 is generally limited in this invention to notgreater than about 50 wt %, based on total weight of butene in thestream. In some cases, the butene stream contains not greater than about40 wt % or 30 wt % butene-1, based on total weight of butene in thestream. Thus, in various embodiments, the butene stream can comprisefrom 10 wt % to 50 wt % or 15 wt % to 40 wt % or 20 wt % to 30 wt %butene-1, based on total weight of butene in the butene stream.

In one embodiment, of the total amount of butenes present in the butenefeed stream used in this invention, at least 40 wt % of the total buteneconcentration is butene-2 (the combined cis and trans forms). In otherembodiments, at least 50 wt %, or 60 wt %, based on total weight ofbutene present in the stream, is butene-2. The concentration of butene-2is generally limited to not greater than about 80 wt %, based on totalweight of butene in the stream. Preferably, the butene stream containsnot greater than about 75 wt %, and more preferably not greater thanabout 70 wt % butene-2, based on total weight of butene in the stream.Thus, in various embodiments, the butene stream can comprise from 40 wt% to 80 wt % or 50 wt % to 75 wt % or 60 wt % to 70 wt % butene-2, basedon total weight of butene in the butene stream.

In one embodiment, of the total amount of butenes present in the butenestream used in this invention, at least 2 wt % of the total buteneconcentration is isobutylene, particularly when the butene feed isobtained from oxygenates. In other embodiments, at least 3 wt %, or 4 wt%, based on total weight of butene present in the stream, isisobutylene. Where butenes obtained from oxygenates are used, theconcentration of isobutylene is generally limited in this invention tonot greater than about 15 wt %, based on total weight of butene in thestream. When a butene stream obtained by the conversion of oxygenates isused, the butene stream contains typically not greater than about 12 wt%, and more typically not greater than about 8 wt % isobutylene, basedon total weight of butene in the stream. Thus, in various embodiments,the butene stream can comprise from 2 wt % to 15 wt % or 3 wt % to 12 wt% or 4 wt % to 8 wt % isobutylene, based on total weight of butene inthe butene stream.

It is also desirable that the butene containing feed stream be separatedso as to contain a lesser amount of propylene. Preferably a butenecontaining feed stream should contain less than about 0.5 wt %propylene, based on total weight of the butene stream. Streamscontaining even lesser amounts of propylene are preferred. For example,butene streams containing not greater than about 0.3 wt % propylene, notgreater than about 0.1 wt % propylene, and not greater than about 0.05wt % propylene, based on total weight of the butene stream, areprogressively more preferred.

It is also desirable that the butene containing feed stream be separatedso as to contain a lesser amount of total pentenes. Preferably a butenecontaining feed stream should contain less than about 0.5 wt % totalpentenes, based on total weight of the butene stream. Streams containingeven lesser amounts of total pentenes are preferred. For example, butenestreams containing not greater than about 0.3 wt % total pentenes, notgreater than about 0.1 wt % total pentenes, and not greater than about0.05 wt % total pentenes, based on total weight of the butene stream,are progressively more preferred.

A butene stream separated and recovered from the olefin product of anoxygenate conversion process requires little if any treatment to removecontaminants. For example, little if any treatment is needed to removecompounds containing sulfur, nitrogen and chlorine, which can act aspoisons to hydroformylation catalysts. In certain cases, however, it mayalso be appropriate to mildly hydrogenate the butene stream to removedienes or acetylenes, which can be present in the butene stream, andwhich can act as temporary inhibitors to the hydroformylation catalyststhat only slowly hydrogenate to the corresponding olefins.

Butenes obtained by cracking hydrocarbon streams can also be used inthis invention. Butenes obtained from such a source can also be combinedwith butenes obtained from an oxygenate conversion reaction. This isbecause the butenes obtained by a cracking process are generally high innon-reactive hydrocarbon components such as alkanes, are high inbranchiness, and are high in other undesirable by-products such assulfur, nitrogen and/or chlorine. Therefore, additional purification ofa butene stream containing butenes obtained from a cracking process maybe needed.

Conventional processes can be used for removing undesirable componentsfrom the olefin feed stream of this invention. Such methods includewater washing, caustic scrubbing, distillation, and fixed bedadsorption. Other desirable methods, such as those found in Kirk-OthmerEncyclopedia of Chemical Technology, 4th edition, Volume 9, John Wiley &Sons, 1996, pg. 894-899, the description of which is incorporated hereinby reference, can also be used. In addition, purification systems suchas that found in Kirk-Othmer Encyclopedia of Chemical Technology, 4thedition, Volume 20, John Wiley & Sons, 1996, pg. 249-271, thedescription of which is also incorporated herein by reference, can beused.

The C4 feed (butene stream) used in this invention preferably has a lowsulfur and/or nitrogen and/or chlorine content. According to oneembodiment, the butene stream also contains acetaldehyde at aconcentration that does not substantially adversely affect the catalyticactivity of the hydroformylation catalyst.

The sulfur content of the butene feed used in this invention should besufficiently low such that the activity of the catalyst used to form thehydroformylated product is not substantially inhibited. Preferably, thesulfur content in the butene feed is not greater than about 10 ppm; morepreferably, not greater than about 5 ppm; and most preferably, notgreater than about 2 ppm by weight, calculated on an atomic basis. Mostpreferably the feed contains below 50 ppb of sulphur and even morepreferably less than 20 or even less than 10 ppb by weight of sulfur.

The nitrogen content, in particular organic nitrogen compounds such ascyanides, of the butene feed used in this invention should also besufficiently low such that the catalytic activity of the catalyst usedto form the hydroformylated product is not substantially inhibited.Preferably, the nitrogen content in the olefin feed is not greater thanabout 10 ppm; more preferably, not greater than about 5 ppm; and mostpreferably, not greater than about 2 ppm by weight, calculated on anatomic basis. Most preferably the feed contains below 50 ppb of nitrogenand even more preferably less than 20 or even less than 10 ppb by weightof nitrogen.

The chlorine content, in particular ionic chlorine, of the butene feedused in this invention should also be sufficiently low such that thecatalytic activity of the catalyst used to form the hydroformylatedproduct is not substantially inhibited. Preferably, the chlorine contentin the olefin feed is not greater than about 5 ppm; more preferably, notgreater than about 2 ppm; and most preferably, not greater than about 1ppm by weight, calculated on an atomic basis. Most preferably the feedcontains below 50 ppb of chlorine and even more preferably less than 20or even less than 10 ppb by weight of chlorine.

The butene stream can contain a non-toxic amount of acetaldehyde,particularly if the butene stream is obtained from the olefin product ofan oxygenate to olefin conversion reaction. This means that acetaldehydewill be present in the stream, which provides the advantage thattreatment or removal is not necessary. However, excessive quantities arenot desirable from a practical standpoint that reactor volume isinefficiently utilized. A butene stream containing up to about 5000 ppmby weight, based on total weight of the butene stream, is highlyacceptable. The lower the quantity of acetaldehyde, the greater thedesirability from a hydroformylation operation standpoint. However,lower quantities of acetaldehyde may mean that at least some removalprocess has been performed. The presence of acetaldehyde at levels ofabout 4000 ppm by weight, about 3000 ppm by weight, about 2000 ppm byweight, about 1000 ppm by weight, about 500 ppm by weight, about 250 ppmby weight, about 100 ppm by weight, based on total weight of the butenestream, are considered acceptable.

A variety of hydroformylation catalysts can be used in this invention.Rhodium catalysts are preferred. Rhodium catalysts containing anorganophosphorus ligand are particularly preferred. Hydroformylationreactions of lower olefins such as ethylene, propylene and butenes havegenerally employed rhodium catalyst stabilised by phosphorus containingligands operated in what is known as the low pressure oxo (LPO)technology originally developed by Union Carbide Corporation andcurrently available under license from Davy Process Technology. Inanother hydroformylation technology, cobalt containing catalysts areused and the process is operated at higher pressures. In a similar wayto cobalt, also rhodium catalysed hydroformylation may be operated athigher pressures, without a stabilizing ligand other than carbonmonoxide or with a weak ligand like e.g. triphenylphosphine oxide(TPPO).

As previously mentioned isobutylene has been considered to be an inertin the low pressure, rhodium catalysed hydroformylation processes thatare offered for license, primarily by Union Carbide Company (now DowChemical Company) and Davy Process Technology (DPT). Older versions ofthis technology use triphenylphosphine (TPP) as the ligand for therhodium catalyst. This ligand forms rather strong complexing bonds withthe rhodium metal, which is noticed by a significant reduction ofactivity as compared to hydroformylation using rhodium without the TPPligand. In order to obtain a high selectivity to the normal aldehydeproduct, preferred over its 2-methyl branched equivalent, they alsotypically use a high phosphorus to rhodium ratio which leads to evenmore reduced reaction rates. In order to be economical, the process istherefore operated at a rather low per pass conversion combined with theuse of significant recycles, which make inerts, such as isobutylene, inthe feeds very undesirable. A newer version of this technology uses abis-phosphite ligand. Its complexing bonds are less strong, yet itsselectivity to the normal aldehyde product is even higher than with TPP.This allows the use of a lower phosphorus to rhodium ratio, such thatthese catalysts are more reactive and therefore can run once-through atacceptable conversions, and the process can use reactors in series. Thebranched product structure of isobutylene has however also beenconsidered undesirable with this catalyst, and therefore the isobutyleneis preferentially removed from the feed, so that typically raffinate-2is also proposed as the preferred feedstock for low pressurehydroformylation, using the bis-phosphite version technology.

Accordingly when using rhodium based low pressure oxo technology withraffinate-1, it has been common practice to separate the isobutylenefrom the normal butenes in the raffinate-1 to produce a streamcontaining only n-butenes which can be used for hydroformylation; such astream is sometimes known as raffinate-2. The separation of isobutylenefrom raffinate-1 is however not an easy process and is expensive andenergy consuming. If fractionation is used, a mixture of butene-1 andisobutene tends to be obtained overhead, whilst the butene-2 tends to beobtained at the bottom of the fractionation tower. Clearly this is notbeneficial if one wants to obtain a butene-1 stream that issubstantially free of isobutylene. Accordingly superfractionation may beused; however, this has very high energy requirements and is expensiveto operate and complex to design. Furthermore, even the use ofsuperfractionation may not result in complete separation of theisobutylene.

We have found that by increasing temperature and/or the partial pressureof carbon monoxide in the low pressure hydroformylation reactionemploying a single, non aqueous liquid phase reaction, isobutylene canbe made to react when using the traditional rhodium based phosphorusliganded catalyst systems. Because the hydroformylation rate isproportional to the H₂ to CO ratio used in the reactor, it is alsopreferable to increase the H₂ partial pressure as well as the carbonmonoxide partial pressure. Consequently, the present invention in one ofits embodiments requires a higher operating pressure, not foreseen in atypical single liquid phase low pressure rhodium based hydroformylationprocess design.

The operation of this process avoids the need for the complicated andexpensive separation of isobutylene from the unsaturated C₄ feed such asraffinate-1.

The C₄ streams that are used in the present invention and that containmore than 2 wt % isobutylene may be obtained from the conversion ofoxygenates to olefins as described above. The preferred feeds containmore than 15 wt % isobutylene and are conveniently those obtained in thesteam cracking or catalytic cracking of hydrocarbon gases, condensatesand/or petroleum feedstocks. The composition of the streams will dependupon the composition of the petroleum feedstock and the conditionsemployed in the steam cracking or catalytic cracking operation.Typically such feeds contain from 15 to 50 wt % isobutylene and from 40to 85 wt % normal butenes, any remainder being primarily n-butane andisobutane. More typically the feeds contain from 18 to 45 wt %isobutylene. The normal butenes are generally a mixture of butene-1 andbutene-2 (cis- and trans-form) and the relative proportions of thosematerials will also depend upon the composition of the petroleum feedand the conditions employed in the steam cracking or catalytic crackingoperation and in the subsequent process steps. This is becauseisomerisation of the double bond of the n-butene readily occurs undermany process conditions, so butene-1 easily converts to butene-2 andvice-versa. A preferred feed however contains from 12% to 30% ofbutene-1 and from 17% to 40% of butene-2. Other materials such as C₃ andC₅ hydrocarbons and trace quantities of butadienes, C₄-acetylenes may bepresent in the C₄ stream.

In particular the C₄ stream from cracking may contain components thatare poisons to the rhodium catalyst or which inhibit thehydroformylation reaction, examples being certain sulphur or chlorinespecies. To the extent that their presence is undesired, they may beremoved or their content reduced by techniques known in the art.

The preferred hydroformylation conditions that are employed convert allthe butenes during the hydroformylation reaction; typically above 80% ofthe butene-1 is converted and above 50% of the isobutylene and of thebutene-2s are converted. We prefer to use rhodium catalysedhydroformylation at low pressures but have found that in order tohydroformylate the isobutylene, higher temperatures and/or longerresidence times and/or higher partial pressure of carbon monoxide areadvantageously used. However, it is desirable to maintain the hydrogento carbon monoxide ratio up during the hydroformylation and so it may benecessary to increase the hydrogen partial pressure also and accordinglya higher overall pressure may be used.

The butene hydroformylation is preferably carried out in the presence ofa catalyst comprising a rhodium complex in conjunction with anorganophosphorus ligand. This organophosphorus ligand may be a tertiaryorganophosphine or an organophosphite. The process employing TPP orother phosphines is typically operated at conditions (high phosphorus torhodium ratio (P/Rh) and low partial pressure of carbon monoxide(p_(CO)) where almost only butene-1 reacts, due to the desire to producea valeraldehyde mixture having a high normal to iso ratio (n/i orn/iso), favouring the production of n-valeraldehyde vs 2-methylbutanal.The triorganophosphine ligand can be for example a trialkylphosphinesuch as tributylphosphine, a C₁-C₆ alkyldiarylphosphine such asbutyldiphenylphosphine, an aryldialkylphosphine such asphenyl-dibutylphosphine, an aryldialkyl diphosphine such ascyclohexyldiphenyl phosphine, tetraphenyldiphosphinomethane,1,2-bis(diphenyl phosphino) ethane, 1,3-bis(diphenyl phosphino) propane,1,4-bis(diphenyl phosphino) butane, and the bisphosphine ligandsdescribed in EP-A 279,018, EP-A 311,619, WO 90/06810 and EP-A 71,281.However particular phosphines such as triphenylphosphine,tri-p-tolylphosphine, trinaphthylphosphine, phenyldinaphthylphosphine,diphenylnaphthylphosphine, tri(p-methoxyphenyl)phosphine,tri(p-cyanophenyl)phosphine, tri(p-nitrophenyl)phosphine,p-N,N-dimethylaminophenylbisphenylphosphine and the like are preferred.Triphenylphosphine (TPP) is most preferred.

Organophosphite ligands can be those disclosed in U.S. Pat. No.4,599,206, U.S. Pat. No. 4,668,651, U.S. Pat. No. 4,737,588, U.S. Pat.No. 4,748,261, U.S. Pat. No. 4,769,498, U.S. Pat. No. 4,774,361, U.S.Pat. No. 4,789,753, U.S. Pat. No. 4,835,299, U.S. Pat. No. 4,871,880,U.S. Pat. No. 4,885,401, U.S. Pat. No. 5,179,055, U.S. Pat. No.5,288,918, U.S. Pat. No. 5,312,996, U.S. Pat. No. 5,364,950, U.S. Pat.No. 5,681,473, U.S. Pat. No. 5,756,855, WO 97/20793. Preferred is6,6′-[[3,3′,5,5′-tetrakis(1,1-dimethylethyl)-[1,1′-biphenyl]-2,2′-diyl]bis(oxy)]bis-dibenzo[d,f][1,3,2]-dioxaphosphepin,or6,6′-[[3,3′,5,5′-tetrakis(1,1-dimethylpropyl)-1,1′-biphenyl]-2,2′-diyl]bis(oxy)]bis-dibenzo[d,f][1,3,2]-dioxaphosphepin,or 6,6′-[[3,3′-bis(1,1-dimethylethyl)-5,5′-dimethoxy[1,1′-biphenyl]-2,2′-diyl]bis(oxy)]bis-dibenzo[d,f][1,3,2]-dioxaphosphepin,or tris(2,4,6-di-t-butylphenyl)-phosphite. Most preferred is6,6′-[[3,3′,5,5′-tetrakis(1,1-dimethylethyl)-1,1′-biphenyl]-2,2′-diyl]bis(oxy)]bis-dibenzo[d,f][1,3,2]-dioxaphosphepin.Ionic varieties of such phosphites are disclosed in U.S. Pat. No.5,059,710 and U.S. Pat. No. 5,113,022.

The hydroformylation process may generally be carried out in a mannerknown by the persons skilled in the art, for example by the processaccording to U.S. Pat. No. 4,247,486, U.S. Pat. No. 4,287,370, U.S. Pat.No. 5,053,551, U.S. Pat. No. 6,100,432, WO 02/00582, DE 10128325although with some of them, higher temperatures and/or longer residencetimes and/or carbon monoxide partial pressures will be used. Thecatalysts employed in the low pressure oxo hydroformylation reactionsare typically rhodium based catalyst that are stabilised by a ligand.Since the advent of rhodium low pressure oxo technology there has been acontinuing evolution of the ligands. The most frequently used ligandshave been triphenylphosphinic, such as discussed above. Those catalystsemploying these ligands would convert primarily butene-1. Accordingly todate, the hydroformylation cycle using rhodium catalyst with suchligands and an isobutylene containing feed involves:

a) removal of the isobutylene from the feedb) subjecting the normal butenes to hydroformylation wherein onlybutene-1 would be converted to valeraldehyde and/or pentanol.c) separation of the unreacted butene-2 from the valeraldehyde and/orpentanol.

The present invention changes this process in that the isobutylene isconverted to useful product during the hydroformylation reaction.

More recently bisphosphite ligands, e.g. of the formula

have been developed and these are described in U.S. Pat. No. 5,364,950,U.S. Pat. No. 4,835,299 and U.S. Pat. No. 5,288,918. We prefer to usethe catalysts employing those ligands in the hydroformylation of C₄feeds containing normal butenes and isobutylene, with high conversionsubstantially of all the unsaturated C₄ materials to usefulvaleraldehyde. These ligands are capable of converting significantportions of all three butenes. Use of these catalysts allows relativelylow P/Rh ratios while maintaining desired product selectivity.

Accordingly the hydroformylation cycle using these phosphite ligandscomprises subjecting a mixed C₄ olefin feed containing isobutylene tohydroformylation under conditions that react substantially all theunsaturated C₄ materials to produce valeraldehyde.

During the hydroformylation reaction it is believed that the carbonmonoxide competes with the phosphorus compound to co-ordinate as ligandsto the rhodium metal. Accordingly a higher carbon monoxide partialpressure will co-ordinate more carbon monoxide with the rhodium and lessof the much more bulky phosphorus containing ligand will co-ordinate. Inthis way the metal in the complex becomes more accessible for olefinbonds that are more substituted, like internal olefins and/or branchedolefins, such as isobutylene. Accordingly by increasing the partialpressure of the carbon monoxide, isobutylene can be made tohydroformylate at acceptable rates, especially with the bis-phosphiteligand system, but also with the older rhodium/triphenyl phosphinecatalyst system. An additional effect of the higher partial pressures ofcarbon monoxide is a higher resistance of the rhodium complex againstthe formation of rhodium clusters, which become less and less activehydroformylation catalysts as more rhodium atoms tie up together, andultimately may come out of solution and form precipitates. As thisdeactivation process goes faster at higher temperatures, the higherpartial pressures of carbon monoxide permit the operation of the processat higher temperatures, and hence bring even greater additional benefitsin terms of reaction rate, which can be translated into productivity,yield and/or investment benefits, or a combination thereof, as thepractitioner may like.

As an extension the valeraldehyde produced by this invention may then beconverted to 2-propyl heptanol or mixtures containing 2-propyl heptanolby dimerisation, usually by an aldol reaction, and hydrogenation.

According to the invention therefore, hydroformylation may beaccomplished using phosphite ligands with careful control of thetemperatures, residence times and partial pressures of the reactantsand/or products. Thus, when a triorganophosphine ligand is used, it ispreferably used in an amount of at least 100 mol per gram atom ofrhodium. Contrarily, if one prefers to forego the high selectivity tothe normal aldehyde, one may use amounts of triorganosphosphine ligandthat are much lower, like 40 or less mole per gram atom of rhodium, butalso 20 or less, and even 10 or less, down to 5 or less, or even 2 orless, should one desire to do so. The residence time required for thetarget conversions is suitably adapted according to the activity of thechosen ligand and the P/Rh ratio. Preferably with bis-phosphite ligandsthe amount of ligand present is from 1 to about 40 moles of bisphosphiteligand per mole of rhodium, more preferably from 1 to 4 moles ofbisphosphite ligand per mole of rhodium, said amount of ligand being thesum of both the amount of ligand that is bound (complexed) to therhodium metal and the amount of free (non-complexed) ligand present. Ifdesired, make-up ligand can be supplied to the reaction medium of theprocess at any time and in any suitable manner, e.g. to maintain apredetermined level of free ligand in the reaction medium. Thetemperature is generally in the range of 50 to 180° C., preferably inthe range from 80 to 155° C., more preferably in the range from 85 to135° C., even more preferably from 85 to 115° C. The total pressure ispreferably not more than 10000 kPa. The partial pressure of carbonmonoxide is preferably kept above 200 kPa but below 5000 kPa; and thatof hydrogen is preferably kept in the range from 100 to 7000 kPa. Wehave found that when using a phosphite ligand such as Ligand A at areaction temperature of 95° C. and a partial pressure of carbon monoxideof about 5 bar, a residence time of greater than 15 minutes results in asignificant conversion of isobutylene.

When a phosphine ligand is used the preferred hydroformylationconditions are a total gas pressure (of hydrogen, carbon monoxide andolefinic unsaturated starting compound) of the hydroformylation processranging from about 1 to about 30,000 kPa. In general, however, it ispreferred that the process be operated at a carbon monoxide partialpressure of at least 0.2 MPa, more preferably at least 0.5 MPa ascompared to the conventional technology which prefers and employs acarbon monoxide partial pressure of below 0.2 MPa. More preferably thecarbon monoxide partial pressure is at least 1 MPa, better even 2.5 MPaor above, or 3.0 MPa or above. The total gas pressure of hydrogen,carbon monoxide and olefinic unsaturated starting compound is preferablymore than about 1500 kPa and more preferably more than about 5000 kPa.The minimum total pressure is limited predominantly by the amount ofreactants necessary to obtain a desired rate of reaction. In general H₂to CO molar ratio of gaseous hydrogen to carbon monoxide may range fromabout 1:10 to 100:1 or higher, the more preferred hydrogen to carbonmonoxide molar ratio being from about 1:1 to about 10:1. Further, thehydroformylation process may be conducted at a reaction temperature fromabout 45° C. to about 180° C., desirably in the range 50 to 180° C. Ingeneral a hydroformylation reaction temperature of about 50° C. to about170° C. is employed for all types of olefinic starting materials, themore preferred reaction temperatures being from about 80° C. to about160° C. particularly 80 to 155° C. especially 85 to 115° C. and mostpreferably from about 100, 110, 120, 130 or 140° C. upwards. We havefound that when using the triphenylphosphine ligand at 110° C. and acarbon monoxide partial pressure of about 5 bar, a residence time of atleast two and a half hours, generally at least three hours is requiredto hydroformylate the isobutylene. It is expected that this residencetime may be further shortened as the concentration of the startingolefin is increased, and as the partial pressure of carbon monoxideand/or the temperature is further increased.

Any of these processes may use any suitable solvent. In general, it ispreferred to employ as solvents one or more valeraldehydes and/or theirliquid condensation by-products that are produced in situ during thehydroformylation process. Rhodium concentrations in the hydroformylationreaction medium may be, for example, in the range from about 10 ppm toabout 1000 ppm, calculated as free rhodium. It is generally preferred tooperate with from about 10 to 500 ppm of rhodium, and more preferablyfrom 25 to 350 ppm of rhodium.

Using a rhodium hydroformylation catalyst, isobutylene will makeprimarily only one product, 3-methyl-butyraldehyde (also called3-methyl-butanal or isovaleraldehyde or isopentyl aldehyde), and littleto no 2,2-dimethyl-propionaldehyde is formed. This3-methyl-butyraldehyde boils at 92.5° C., and is thus in practical termsinseparable by distillation from 2-methyl-butyraldehyde, which boils at92.0° C. Both can (together) be distilled off from n-valeraldehyde,boiling at 103° C. (all at 1 atm). N-valeraldehyde and2-methyl-butyraldehyde are the products of n-butene hydroformylation,and due to the higher oxonation rate of these n-butenes, are expected tobe present in the product from the low pressure hydroformylation ofraffinate-1. As alcohols these two monomethyl branched isomers remaindifficult to separate, although their boiling points are further apart(131.4° C. for 3-methyl and 128° C. for 2-methyl butanol). As acids, theboiling points are again very similar (176.5° C. (3-Me) vs 177° C.(2-Me)). Although the two isomers may show different reactivities inseveral of the derivatisation reactions, most technical end-uses are notexpected to be very sensitive to the location of the methyl branch onthe alkyl chain, and the mixed product of this invention should beuseful in the manufacture of alcohols for solvents, plasticisers,esters, xanthogenates, ZDDP; acids for esters as solvents, softeners,perfumes, synlubes, synlube additives. Other derivatives may be isomersensitive, like alcohols for dehydration to isoprene (2-Me) andisoleucine, pinacol or pinacolone into pesticides or butizides inpharmaceuticals, or acids into fungicides, rodenticides, sedatives,narcotics and other drugs in which case separation of the isomers willbe required at some step in the production process.

The invention has the benefit that a larger amount of valeraldehyde isobtained and in an extension of the present invention the valeraldehydeisomer mixture, as produced or a fraction thereof obtained bypurification, is converted into 2 propyl heptanol or mixtures thereofwith other alcohols preferably by aldol condensation followed byhydrogenation. In another extension the valeraldehyde or valeraldehydemixture is hydrogenated to pentanol or pentanol mixtures or oxidised topentanoic acid or mixtures of pentanoic acids.

The invention therefore provides a substantial improvement in theoverall conversion and utilisation of C₄ refining streams avoiding theneed for hitherto expensive and complex techniques for the separation ofisobutylene from the C₄ refinery stream.

Butene hydroformylation has traditionally only been considered onraffinate-2 streams, from which isobutylene has been removed down to 1%wt or below, because of the higher upgrade achieved when converted toMtBE, EtBE, Butyl rubber, DIB/TIB or PIB. The current concept is tohydroformylate the streams with the isobutylene in them. Characteristicis the presence of 3-methyl-butanal, and also the low level of alcohols.Other C₅ aldehydes possible are n-valeraldehyde and 2-methyl-butanal.2,2-dimethyl-propanal, if present, will be low due to the use of rhodiummetal. Cobalt will give higher alcohol levels and higher presence of2,2-dimethylpropanal/ol. The level of 3-methyl-butanal in this C₅aldehyde mix depends on the choice of butene feedstock (level ofisobutylene vs other butenes) and the choice of low pressurehydroformylation technology (conversion of the isobutylene vs the otherbutenes).

Isobutylene containing C₄ olefinic streams vary depending on theirsource and treatment. Table 1 shows some typical compositions.

TABLE 1 C4 feeds containing isobutylene Steamcracker Crude C4's MTOTypical comp. FCC After BD After Sel. After Sel. Wt % C4 cut extractionHydro Hydro Stream ID F1 F2 F3 F4 Isobutylene 22 47 29 4 Butene-1 14 2529 21-24 Butene-2 cis 12 8 10 27 Butene-2 trans 17 10 24 40-41 n-Butane7 8 7 4-8 Isobutane 24 1 1 .3 96 99 100 100 Remainder C3-5s, BD BD — FCC= Fluid Catalytic Cracking BD = Butadiene MTO = Methanol (or otheroxygenates) To Olefins Sel. Hydro = Selective Hydrogenation

The C₅ aldehyde product mixtures obtained by the hydroformylation ofsuch streams vary according to the composition of the feed and thehydroformylation technology deployed on them.

The amount of 3-methyl-butanal in the product mix will also depend onthe conversion of isobutylene vs the other butenes, which one may beable to influence by ligand selection, by temperature, by residence timeand by partial pressure of CO(P_(CO)) in the reactor. The order ofreactivity of the butenes is typically butene-1>butene-2(cis/trans)>isobutylene.

Higher p_(CO) will tend to shift the ligand equilibrium to complexesthat are more accessible by branched (and internal) olefins. So, it isexpected that also Rh/phosphine technology may be made suitable forisobutylene conversion provided that the p_(CO) can be raised.

The following C₅ aldehyde mixtures are predicted from the feedsdescribed in Table 1 using the two ligand families discussed:

TABLE 2 C₅ aldehyde product mixes Ligand family Phosphines Phosphites %Conversion of Butene-1 85 99 Butene-2 43 63 Isobutylene 17 48 N/iso (onn-C4s) 10 30 Feed stream ID F1 F2 F3 F4 F1 F2 F3 F4 n-Valeraldehyde 7871 80 93-94 73 59 76 94  2-Me-butanal  8  7  8 3  2  2  2 3 3-Me-butanal14 22 12 3-4 25 39 22 3 2,2-diMe-propanal — — — — — — — —

The traditional hydroformylation of raffinate-2 feed (1% wtisobutylene), irrespective of its source—steamcracker or FCC, willinevitably give less than 1% wt 3-Me-butanal in the C₅ aldehyde mix.

The product of the hydroformylation reaction will generally requireadditional purification. Rhodium catalysed hydroformylation is employedand typically the reaction products are taken from the reactor as vapourand then condensed, although in some systems they can also be taken offas liquid which is subjected to a subsequent flash. The vapours obtainedare then split into the paraffins, the aldehydes, the remaining olefins,unreacted feeds including carbon monoxide and hydrogen which can berecycled, and the heavies. Optionally also a portion of the remainingolefins, possibly containing also some paraffins, may be recycled.

The above C₅ aldehyde streams may be hydrogenated to alcohols oroxidised to acids using standard technology to produce mixtures with thesame isomer backbone compositions, and which have some commercialrelevance.

The composition of the alcohols and acids produced is set out in Table3.

TABLE 3 C₅ alcohol and acid product mixes Ligand family PhosphinesPhosphites Feed stream ID F1 F2 F3 F4 F1 F2 F3 F4 Alcohol product:n-Amyl alcohol 78 71 80 93-94 73 59 76 94  2-Me-butanol  8  7  8 3  2  2 2 3 3-Me-butanol 14 22 12 3-4 25 39 22 3 2,2-diMe-propanol — — — — — —— — Acid product: n-Valeric acid 78 71 80 93-94 73 59 76 94 2-Me-butanoic  8  7  8 3  2  2  2 3 3-Me-butanoic 14 22 12 3-4 25 39 223 2,2-diMe-propanoic — — — — — — — —

Accordingly the present invention further provides a C₅ alcohol mixtureconsisting essentially of normal and mono-methyl branched alcohols andcomprising n-pentanol, 2-methyl-butanol and 3-methyl-butanol wherein

-   -   i. n-pentanol and 2-methyl-butanol are present in a ratio from        3:1 to 100:1 and    -   ii. 3-methyl-butanol and 2-methyl-butanol are present in a ratio        of at least 0.3:1.

In such C5 alcohol mixture the ratio of 3-methyl-butanol to2-methyl-butanol is preferably at least 0.5:1, more preferably at least1:1, yet more preferably at least 10:1 and most preferably at least20:1. For example the ratio is preferably in the range 0.3:1-30:1, morepreferably 0.5:1-25:1 and most preferably 1:1-20:1. The ratio ofn-pentanol to 2-methyl-butanol is preferably in the range 5:1-50:1, morepreferably 8:1-40:1, yet more preferably 10:1-35:1 such as 15:1-35:1,and most preferably 20:1-30:1.

In a further embodiment the invention also provides a C₅ acid mixtureconsisting essentially of normal and mono-methyl branched acids andcomprising n-pentanoic acid, 2-methyl-butanoic acid and3-methyl-butanoic acid wherein

-   -   i. n-pentanoic acid and 2-methyl-butanoic acid are present in a        ratio from 3:1 to 100:1 and    -   ii. 3-methyl-butanoic acid and 2-methyl-butanoic acid are        present in a ratio of at least 0.3:1.

In such C5 acid mixture the ratio of 3-methyl-butanoic acid to2-methyl-butanoic acid is preferably at least 0.5:1, more preferably atleast 1:1, yet more preferably at least 10:1 and most preferably atleast 20:1. For example the ratio is preferably in the range 0.3:1-30:1,more preferably 0.5:1-25:1 and most preferably 1:1-20:1. The ratio ofn-pentanoic acid to 2-methyl-butanoic acid is preferably in the range5:1-50:1, more preferably 8:1-40:1, yet more preferably 10:1-35:1 suchas 15:1-35:1, and most preferably 20:1-30:1.

The invention therefore also provides for mixtures of valeraldehydesthat are novel, as produced by the rhodium based hydroformylation ofraffinate-1 streams characterised by significant conversions ofisobutylene. These valeraldehyde mixtures are characterised by a lowcontent of C₅ alcohols, being 30% or less by weight, preferably 16% orless, more preferably 6% or less, most preferably 3% or less. They arealso characterised by a significant presence of 3-methyl-butanal or“isovaleraldehyde”, generally being below 96%, 92% or 80%, but at aminimum of 10% or higher, more typically 20% or higher, preferably 24%or above, more preferably 26% or higher, most preferably 36% or higher.The remainder of the mixture is primarily composed of n-valeraldehydeand 2-methyl-butyraldehyde. Depending on the choice of phosphorusligand, the relative ratio of these two can differ between 3:1normal-to-branched, up to 30 or even 40:1 normal-to-branched ratio. Thepresence of 2-methyl-butyraldehyde can therefore be low, like 1.5%, or2% by weight, up to 3 or 4% by weight, or it can be more significant,like 6% or 7% by weight, up to 9 or 10% by weight. N-valeraldehydepresence in the mixtures can conversely be as low as 50-55% by weight,or can be higher at around 70-75%, or even higher still, at 78-84% byweight.

These aldehyde mixtures can be submitted to aldolisation, as such, orafter partial (or complete) separation of the branched valeraldehydesfrom n-valeraldehyde. 3-methyl-butyraldehyde is able to participate inaldolisation, and in two ways as shown below, as it has two alphahydrogens to the carbonyl bond. The same applies to n-valeraldehyde, butnot to 2-methyl-butyraldehyde. An aldolisation of a mix of the threevaleraldehydes will therefore produce a mixture of the following enals.The reactions are described in the sequence of the expected rate ofaldolisation:

Fastest

n-valeraldehyde+n-valeraldehyde→2-(n)-propyl-2-heptenal(1+1)

Slower

2-Me-butanal+n-valeraldehyde→2-(n)-propyl-4-methyl-2-hexenal(1+2)

3-Me-butanal+n-valeraldehyde→2-(n)-propyl-5-methyl-2-hexenal(1+3)

n-valeraldehyde+3-Me-butanal→2-isopropyl-2-heptenal(3+1)

Slowest

2-Me-butanal+3-Me-butanal→2-isopropyl-4-methyl-2-hexenal(2+3)

3-Me-butanal+3-Me-butanal→2-isopropyl-5-methyl-2-hexenal(3+3)

The production of C10 aldehydes by the aldol condensation of C₅aldehydes produced from feeds with low levels of isobutylene isdescribed in U.S. Pat. No. 6,340,778 and WO 03/029180, and theseprocesses can be used in the present invention.

The present invention therefore further provides an unsaturated aldehydemixture comprising: 2-isopropyl-2-heptenal; 2-propyl-2-heptenal;2-propyl-5-methyl-2-hexenal; 2-propyl-4-methyl-2-hexenal and2-isopropyl-4-methyl-2-hexenal containing at least 20%2-propyl-2-heptenal and wherein the ratio of the combined amount of2-isopropyl-2-heptenal and 2-propyl-5-methyl-2-hexenal to the combinedamount of 2-propyl-4-methyl-2-hexenal and 2-isopropyl-4-methyl-2-hexenalis at least 0.3. Such ratio is preferably at least 0.5, more preferablyat least 1.0, yet more preferably at least 10 and most preferably atleast 20. For example the ratio is preferably in the range 0.3-30, morepreferably 0.5-25 and most preferably 1-20.

Such unsaturated aldehyde mixture may be hydrogenated selectively tosaturate only the C═C double bond, to the equivalent saturated aldehydemixture, using methods described below.

In a further embodiment the invention therefore provides an aldehydemixture comprising: 2-isopropyl heptanal; 2-propyl heptanal;2-propyl-5-methyl hexanal; 2-propyl-4-methyl hexanal and2-isopropyl-4-methyl hexanal containing at least 20% 2-propyl heptanaland wherein the ratio of the combined amount of 2-isopropyl heptanal and2-propyl-5-methyl hexanal to the combined amount of 2-propyl-4-methylhexanal and 2-isopropyl-4-methyl hexanal is at least 0.3. Such ratio ispreferably at least 0.5, more preferably at least 1.0, yet morepreferably at least 10 and most preferably at least 20. For example theratio is preferably in the range 0.3-30, more preferably 0.5-25 and mostpreferably 1-20.

Alternatively the unsaturated aldehyde mixture may be hydrogenatedselectively to saturate only the C═O double bond, to the equivalentunsaturated alcohol mixture. Osmium, rhenium and particularly platinum(possibly in an inhibited form) are suitable hydrogenation catalystsherefore.

In yet a further embodiment the present invention therefore provides anunsaturated alcohol mixture comprising: 2-isopropyl-2-heptenol;2-propyl-2-heptenol; 2-propyl-5-methyl-2-hexenol;2-propyl-4-methyl-2-hexenol and 2-isopropyl-4-methyl-2-hexenolcontaining at least 20% 2-propyl-2-heptenol and wherein the ratio of thecombined amount of 2-isopropyl-2-heptenol and2-propyl-5-methyl-2-hexenol to the combined amount of2-propyl-4-methyl-2-hexenol and 2-isopropyl-4-methyl-2-hexenol is atleast 0.3. Such ratio is preferably at least 0.5, more preferably atleast 1.0, yet more preferably at least 10 and most preferably at least20. For example the ratio is preferably in the range 0.3-30, morepreferably 0.5-25 and most preferably 1-20.

The condensation of two molecules of an aldehyde to form an aldol,usually followed immediately by dehydration, to form an unsaturatedaldehyde with twice the original number of carbon atoms (or the sum ofthe carbon atoms of two different aldehydes in a cross-aldolisation) iswell known, as are the conditions required to effect the condensation.In general, the reactants may be either in the vapour or liquid phase,at moderately elevated temperatures, e.g., from 40° C. to 200° C., andpressures, e.g., from 0.01 to 2 MPa, preferably from 0.1 to 2 MPa. Thereaction is generally carried out in the presence of a catalyst, whichmay be solid or liquid, and either acidic or, preferably, basic.Although organic bases may be used, a, preferably strong, inorganicbase, for example an alkali metal hydroxide or carbonate, is preferred,advantageously in the form of an aqueous solution. In other embodimentsa solid catalyst, e.g., a metal oxide, especially a titanium ormagnesium oxide, may be used. The above conditions apply generally tothe aldol process steps of the present invention; under the preferredconditions dehydration is very fast and essentially complete.

If it is desired to make the saturated C₁₀ aldehyde from the immediateproduct of the aldolisation, further hydrogenation may be effected asdescribed above. This procedure is conveniently also used if the desiredend product is the corresponding mixture of branched C10 acids, producedby oxidation of the C₁₀ aldehyde.

If, however, the desired product is the saturated alcohol mixture, thenmore vigorous hydrogenation conditions may if desired be employed,hydrogenation of the ethylenic unsaturation and reduction of thecarbonyl group taking place at the same time. For this purpose, thereaction may be carried out under conditions and in the presence ofcatalyst systems known per se. For example, the catalyst may be Ni,Raney Ni, Pt or Pd, partially reduced copper oxides, copper/zinc oxides,copper chromite, the copper-based catalyst advantageously being used incombination with cobalt or nickel catalysts; Ni/Mo; Co/Mo or Mo oncarbon, optionally in their sulphided form. Any of the above catalystsmay be used alone or in combination; nickel is the preferred catalyst.The conditions may include, for example, a hydrogen pressure from 2 to30 MPa and a temperature in the range of 100 to 240° C.

Hydrogenation of these C₁₀-enal mixtures, by methods known in the art,will produce the mixture of the corresponding alcohols. Selectivehydrogenation of these enal mixtures, by methods also known in the art,e.g. as disclosed in U.S. Pat. No. 6,090,986 applied on2-methyl-2-pentenal, will produce the mixture of the correspondingsaturated aldehydes. These can then be further hydrogenated to thecorresponding alcohols, but are even more interesting as intermediatesfor oxidation, by methods also known in the art, catalytic ornon-catalytic, with oxygen or air or using another oxygen donor, to thecorresponding mixture of carboxylic acids. Alternatively, thesealdehydes can be used as fragrance components by themselves, or asintermediates for other fragrance and fine chemical components, likeamines. The alcohols and acids are of interest e.g. as feedstocks foresterification, sulfation or alkoxylation possibly followed bysulfation.

Certain mixtures of these C₁₀-enals, or their corresponding alcohols andacids, and their derivatives are considered novel compounds as therhodium-based hydroformylation product of isobutylene has previously notbeen made together with the hydroformylation product of butene-1 and/orbutene-2. This is because isobutylene has for the last 2-3 decades had ahigher value into Methyl tertiary Butyl Ether (MtBE) and Ethyl tertiaryButyl Ether (EtBE) as gasoline oxygenates and octane boosters. Thesenovel C₁₀ aldehydes, alcohols and acids, or their derivatives, couldfind use, and benefits, in end-uses such as plasticisers, surfactants,synlubes, fuel additives, adhesives, fire retardants, fragrances andmetal salts.

The invention therefore further provides an alcohol mixture comprising:2-isopropyl heptanol; 2-propyl heptanol; 2-propyl-5-methyl hexanol;2-propyl-4-methyl hexanol and 2-isopropyl-4-methyl hexanol containing atleast 20% 2-propyl heptanol and wherein the ratio of the combined amountof 2-isopropyl heptanol and 2-propyl-5-methyl hexanol to the combinedamount of 2-propyl-4-methyl hexanol and 2-isopropyl-4-methyl hexanol isat least 0.3. Such ratio is preferably at least 0.5, more preferably atleast 1.0, yet more preferably at least 10 and most preferably at least20. For example the ratio is preferably in the range 0.3-30, morepreferably 0.5-25 and most preferably 1-20.

In a further embodiment the invention provides an acid mixturecomprising: 2-isopropyl heptanoic acid; 2-propyl heptanoic acid;2-propyl-5-methyl hexanoic acid; 2-propyl-4-methyl hexanoic acid and2-isopropyl-4-methyl hexanoic acid containing at least 20% 2-propylheptanoic acid and wherein the reaction of the combined amount of2-isopropyl heptanoic acid and 2-propyl-5-methyl hexanoic acid to thecombined amount of 2-propyl-4-methyl hexanoic acid and2-isopropyl-4-methyl hexanoic acid is at least 0.3. Such ratio ispreferably at least 0.5, more preferably at least 1.0, yet morepreferably at least 10 and most preferably at least 20. For example theratio is preferably in the range 0.3-30, more preferably 0.5-25 and mostpreferably 1-20.

The mixtures of C₁₀-enals, their corresponding mixtures of saturatedaldehydes, alcohols and acids derived from them, including the furtherderivatives of those, will thus be characterised in the presence of thealdol products of 3-methyl-butyraldehyde. At the enal level, this meansthat 2-(n)-propyl-5-methyl-2-hexenal and/or 2-isopropyl-2-heptenal willeach independently be present in the mixture for 2% by weight or more,preferably 3% or more, more preferably 5% or more, even more preferably6% or more, up to 10% or more, and even 11 or 12% by weight. Also2-isopropyl-4-methyl-2-hexenal and 2-isopropyl-5-methyl-2-hexenal can bepresent, but are expected to be present at a lower level at about 0.05%by weight or higher, possibly 0.1% by weight or 0.5%, up to 2 to 2.5% byweight. The remainder of the C₁₀ component mixture is composed of theother aldol products or derivatives, which at the enal level isprimarily 2-propyl-2-heptenal, and this at levels of 74% or above,possibly 86% or above, as high as 91% or 92% by weight. However, if aportion of the n-valeraldehyde is separated off before the aldolisationstep, the presence of 2-propyl-2-heptenal or its equivalent will becorrespondingly lower and the other components, incorporating branchedvaleraldehydes, will be correspondingly higher. The resulting content of2-propyl-2-heptenal may then be as low as 60%, even lower at 50%, orstill lower at 40% by weight on the basis of the total weight of theC₁₀-enals present in the mixture. The compositions of the correspondingaldehydes, alcohols and/or acid derivatives will be correspondinglyleaner in the 2-propylheptyl isomer.

As a result of aldolisation, the invention also provides for aldehydeproducts containing mixtures of various aldol products of the variousvaleraldehydes. In other words, the C₅ aldehyde products of thisinvention can be aldolized to form a mixture of C₁₀ aldehydes,particularly a mixture of C₁₀-enals. In one embodiment, there isprovided an aldehyde mixture comprising at least 85 wt % more preferablyat least 90 wt % 2-propyl-2-heptenal, based on total amount of aldehydesin the mixture. Preferably, the aldehyde mixture comprises at least 92wt % 2-propyl-2-heptenal, more preferably at least 94 wt %2-propyl-2-heptenal, and most preferably at least 96 wt %2-propyl-2-heptenal, based on total amount of aldehydes in the mixture.

In one embodiment, the aldolized product contains a low amount of2-(n)-propyl-4-methyl-2-hexenal. The amount of2-(n)-propyl-4-methyl-2-hexenal present in the aldehyde mixture shouldbe not greater than 2 wt %, based on total amount of aldehydes in themixture. Preferably, the aldehyde mixture comprises not greater than 1.9wt % 2-(n)-propyl-4-methyl-2-hexenal, more preferably not greater than1.8 wt %, and most preferably not greater than 1.7 wt %2-(n)-propyl-4-methyl-2-hexenal, based on total amount of aldehydes inthe mixture.

In general, the aldehyde product that is formed in the aldolisationprocess will contain a measurable quantity of 2-isopropyl-2-heptenal. Itis desirable, however, that the aldehyde composition contain not greaterthan 2 wt % 2-isopropyl-2-heptenal, based on total amount of aldehydesin the mixture. Preferably, the aldehyde composition contains notgreater than 1.9 wt % 2-isopropyl-2-heptenal, more preferably notgreater than 1.8 wt % 2-isopropyl-2-heptenal, and most preferably notgreater than 1.7 wt % 2-isopropyl-2-heptenal, based on total amount ofaldehydes in the mixture. Generally, the aldehyde composition willcontain at least 0.1 wt %, or 0.5 wt % or 1 wt % or 1.5 wt %,2-isopropyl-2-heptenal, based on total amount of aldehydes in themixture.

The aldehyde mixtures of the invention (e.g., the C₅ and C₁₀ aldehydemixtures) can be used as fragrance components by themselves or asintermediates for other fragrance and fine chemical components, likeamines.

The C10 derivatives are of particular potential commercial relevance.Two C₅ aldehydes will combine to a C₁₀ aldol condensation product, whichmost often dehydrates to the unsaturated aldehyde or “enal”. Not allcombinations are possible, only the following isomers will form to anydecent extent:

TABLE 4 Aldol products formed from C5 aldehydes # C10 enal Shortcode 12-propyl-2-heptenal 2ph 2 2-(n)-propyl-4-Me-hexenal 2p4mh 32-(n)-propyl-5-Me-hexenal 2p5mh 4 2-isopropyl-2-heptenal 2iph 52-isopropyl-4-Me-2-hexenal 2ip4mh 6 2-isopropyl-5-Me-2-hexenal 2ip5mh

Isomers numbered 3, 4, 5 and 6 will be characteristic from thehydroformylation of isobutylene-based products. Raffinate-2 basedproducts will give almost exclusively isomers 1 and 2.

The aldolisation reactions mentioned above run at different rates.However, any commercial aldolisation process will prefer to force highconversion of all aldehydes, including the branched ones, if necessaryby recycling unreacted C₅ aldehydes. The compositions of the enalproduct mixes may therefore be predicted as follows:

TABLE 5 C₁₀ product composition mixtures Ligand family PhosphinesPhosphites Feed stream ID C10 product: # F1 F2 F3 F4 F1 F2 F3 F4 2ph 163 51 66 80 51 25 56 89 2p4mh 2 10 7 11 17 1 0 1 4 2p5mh 3 14 23 11 1 2945 25 3 2iph 4 7 11 6 0.6 14 22 13 2 2ip4mh 5 6 7 5 1 4 3 4 2 2ip5mh 60.5 1 0.3 0 2 4 1 0

If it is desired to maintain a number of options for the use of thesaturated C₁₀ aldehyde, the present invention also provides for atwo-stage hydrogenation of the unsaturated aldehyde, the first stagebeing carried out in the presence of a mild catalyst, for example, apalladium catalyst as mentioned above, in a first reactor, yielding thesaturated aldehyde. This may be further hydrogenated using one of thestronger catalysts mentioned above, for example, Ni, in a secondreactor. This procedure has the advantage, in addition to flexibility,of facilitating better control of the hydrogenation reaction which, ifcarried out in a single reactor from unsaturated aldehyde to saturatedalcohol, may give an excessive temperature increase because of the heatreleased on simultaneous hydrogenation of two bonds. The need to controlsuch a highly exothermic reaction adds to reactor costs.

Oxidation of the saturated aldehyde to the corresponding carboxylic acidmay be carried out by any method known per se, i.e., practised in theart or described in the literature. Oxidation is conveniently carriedout using oxygen, if desired or required in the presence of a catalyst.As catalyst there may be mentioned a solution containing metalliccations, e.g., copper, cobalt or manganese.

The C₁₀ alcohols—and their phthalate ester derivatives, will haveparticular importance. Hydrogenation and/or oxidation to the C₁₀aldehydes, acids and alcohols will not change the isomer mixturecomposition. The compositions of the aldehyde, acid and alcohol mixturescan therefore be found in Table 5, by assuming the C₁₀ product shortcode stands for respectively the equivalent given in Table 6.

TABLE 6 C₁₀ product isomer names Short code Aldehyde Acid Alcohol 2ph2-propyl-heptanal 2-propyl-heptanoic 2-propyl- heptanol 2p4mh2-Pr-4-Me-hexanal 2-Pr-4-Me-hexanoic 2-Pr-4-Me- hexanol 2p5mh2-Pr-5-Me-hexanal 2-Pr-5-Me-hexanoic 2-Pr-5-Me- hexanol 2iph2-iPr-heptanal 2-iPr-heptanoic 2-iPr-2- heptanol 2ip4mh2-iPr-4-Me-hexanal 2-iPr-4-Me-hexanoic 2-iPr-4-Me- hexanol 2ip5mh2-iPr-5-Me-hexanal 2-iPr-5-Me-hexanoic 2-iPr-5-Me- hexanol Wherein: Me =methyl Pr = (normal)-propyl iPr = isopropyl

When the C₁₀ alcohol mixtures will be reacted with phthalic anhydride tothe diester, the content of true di-2-propylheptyl-phthalate (DPHP) willbe of the order of as shown in Table 7. The other di-esters will have atleast one alkyl chain that is other than “2ph”:

TABLE 7 DPHP content of phthalate derivative Ligand family PhosphinesPhosphites Feed stream ID C10 phthalate F1 F2 F3 F4 F1 F2 F3 F4 TrueDPHP (wt %) 40 26 44 64 26 6 31 79

The compositions of these mixtures of C₁₀ oxygenates, be it enals,aldehydes, alcohols or acids, may be determined by conventionalchromatographic techniques (GC or HPLC), optionally combined with massspectrometry (GC-MS).

After the hydroformylation step, the unreacted remaining butylenes,together with the butanes that came with the feed and those that wereformed as by-product in the process, may be separated off as aby-product stream. This stream may be used in one or more of theconventional ways for using C₄ hydrocarbons. These include their use orrecycle as steamcracker furnace feed or catalytic cracker feed toproduce more ethylene, propylene and other cracking products or gasolinecomponents, as feed or recycle to a reformer or a partial oxidation oran autothermal reforming unit to produce synthesis gas, which ispotentially useful in the hydroformylation step described before, as LPGblend stock, optionally after further hydrogenation treatment, asalkylation feed, either as such or after full or partial saturation, inwhich case the increased isobutane content is beneficial to the yieldand product quality of the alkylation process. After hydrogenation, theresulting butane streams may also be used or sold, as such or afterseparation of the normal butane from the isobutane, e.g. as specialtysolvents or propellants for spray cans or as blowing agents for foamproduction.

In one embodiment, the butene stream is hydroformylated (i.e.,catalytically reacted with carbon monoxide and hydrogen) to convert atleast 15 wt % of the butene-2 to aldehyde product. Preferably, thebutene stream is hydroformylated to convert at least 20 wt % of thebutene-2, more preferably at least 25 wt % of the butene-2.

The aldehydes, alcohols, acids, and other derivatives of this inventioncan also be used as plasticizers, surfactants, synlubes, fuel additives,adhesives, fire retardants, refrigerant oils and metal salts. In thecase of refrigerant oils, one or more of the alcohols or acids of theinvention are esterified, and the resulting ester composition iscombined with a refrigerant, particularly a fluorohalogen, to form arefrigerant working fluid. The specific compounds in the mixtures ofaldehydes (including enals), alcohols, acids, or esters can bedetermined by conventional chromatographic techniques, such as gaschromatography (GC) or high pressure liquid chromatography (HPLC). Massspectrometry (MS), optionally integrated with chromatography, can alsobe used.

The C₁₀ acids produced by the process of the invention have utility inthe manufacture of alkyd resins, synthetic lubricants and refrigerantoils. The esters of the C₁₀ acids with monohydric alcohols, especiallyalkanols, having at least 6 carbon atoms, especially from 6 to 24, andmore especially from 6 to 12, carbon atoms, have especial utility aslubricants and lubricant components. Also especially useful in thisfield are the esters of the C₁₀ acids with polyhydric alcohols, i.e.,those containing at least two hydroxy groups, for example,pentaerythritol, di(pentaerythritol), tri(pentaerythritol);trimethylolethane, trimethylolpropane, trimethylolbutane, and dimers andtrimers thereof; and neopentylglycol.

The invention accordingly also provides an ester of a monohydric alcoholhaving at least 6 carbon atoms, especially from 6 to 24, more especiallyfrom 6 to 12, carbon atoms, and such an acid mixture. The inventionfurther provides an ester of a polyhydric alcohol and such an acidmixture.

The acid derivatives, especially their esters, have especial utility inproviding components for biodegradable lubricant systems. Oxidativelystable lubricants may be made by partial esterification of a polyol withthe C₁₀ acid, i.e., esterification leaving an unreacted hydroxy group inthe molecule. The metal salts of the acid have utility as catalysts,paint dryers, and PVC stabilizers, while the peroxy esters of the acidare useful as polymerization initiators.

The C₁₀ aldehydes are valuable intermediates, especially in themanufacture of C₁₀ amines, ether amines, and components for thefragrance industry, for example, through condensation with benzaldehyde.

As indicated above, the saturated C₁₀ alcohols produced by the processof the invention, themselves have utility as processing aids in thethermoplastics and textile industries and as solvents for coatings andpaints. They are useful as intermediates in the manufacture of ethers,for example, ethoxylate and other detergent bases such as sulfates andalkoxysulfates. They are especially valuable as intermediates in themanufacture of esters suitable for use as solvents, paint coalescers,plasticizers, adhesives, viscosity index improvers, syntheticlubricants, lubricant components, hydraulic fluids, cetane improvers,drilling fluids, thermoplastic and textile processing aids,polymerizable monomers (e.g., with acrylic and methacrylic acids) andfragrances, by reaction with appropriate acids, for example, by reactionwith monobasic or polybasic, e.g., tribasic or more especially dibasicacids, or where appropriate derivative of the acids, e.g., anhydrides,or by transesterification with other, e.g., methyl, esters.

The acid may be inorganic or organic; if the latter, carboxylic acidsare preferred. Among organic acids, aromatic acids are preferred forplasticizer manufacture, although aliphatic acids are also employed. Asexamples of acids, acetic, and its homologues, e.g., propionic, acids,acrylic, neodecanoic, lauric, stearic, iso-stearic, erucic, phthalic(1,2-benzenedicarboxylic), isophthalic, terephthalic, adipic, fumaric,azelaic, sebacic, trimellitic, pyromellitic, benzoic, cyclohexanoic,cyclohexanoic dibasic, tall oil, napthenic and napthalene-type acids,carbonic, phosphoric and phosphorous, acids and C₆ to C₁₃ oxo and neoacids generally may be mentioned. Esters with monobasic and dibasicacids are preferred for lubricants and lubricant components;advantageously the resulting esters contain from 15 to 40 carbon atoms;adipates and phthalates are especially preferred for lubricantmanufacture.

The invention accordingly also provides an ester of the alcohol mixtureof this invention with a polybasic acid, especially an ester with adibasic acid. The invention also provides an ester of a polybasic acidin which all the acid groups are esterified by the alcohol mixture ofthis invention, especially a dibasic acid both acid groups of which arethereby esterified. Among specific esters provided by the inventionthere may be mentioned, esters of 1,2-benzenedicarboxylic andhexanedioic acids and the tris ester of 1,2,4-benzenetricarboxylic acid,which find use as plasticisers for polymers particularly polyvinylchloride. The phthalate ester also has advantages in the manufacture ofautomotive sealant compositions in part because of their increasedviscosity and enhanced viscosity stability of the composition. Itsoxidative stability, stain resistance and foaming properties arecomparable with those of Jayflex DINP®, di-isononylphthalate ofExonMobil Chemical Company.

The esters may be produced by methods known per se or described in theliterature from the alcohol and the relevant acid or, preferably, whereappropriate, the anhydride, optionally in the presence of a solvent.Elevated temperatures and reduced pressures are generally employed todrive the reaction toward completion by removal of the water produced.Catalysts may be employed. Suitable catalysts include, for example, atitanium catalyst e.g., a tetraalkyl titanate, especiallytetra-iso-propyl or tetraoctyl ortho titanate, or a sulphonic acid,e.g., p-toluene sulphonic acid or methylsulphonic acid. Any catalystpresent in the reaction product may be removed by alkali treatment andwater washing. Advantageously, the alcohol is used in slight, e.g., from10 to 25%, molar excess relative to the number of acid groups in theacid.

The esters may be used as a plasticizer for numerous polymers, forexample, cellulose acetate; homo- and copolymers of aromatic vinylcompounds e.g., styrene, or of vinyl esters with carboxylic acids e.g.,ethylene/vinyl acetate copolymers; halogen-containing polymers,especially vinyl chloride homo- and copolymers, more especially thosecopolymers with vinyl esters of carboxylic acids, esters of unsaturatedcarboxylic acids e.g., methacrylates, and/or olefins; nitrile rubbers;and post-chlorinated vinyl chloride polymers. Poly(vinyl chloride) is ofespecial interest.

The proportion of plasticizer may vary within wide limits, but isgenerally 10 to 200 parts by weight per 100 parts of polymer, moreespecially 20 to 100 parts per 100.

The esters of the invention may be used alone as plasticizer, or inadmixture with other plasticizers, for example, dibutyl, dipentyl,dihexyl, diheptyl, dioctyl, dinonyl, didecyl, diundecyl, didodecyl,ditridecyl phthalates, trimellitates or adipates, each time includingthe normal and branched alkyl chain equivalents, or butyl benzylphthalate, or mixtures thereof. They may also or instead be used with asecondary plasticizer, e.g., a chlorinated paraffin, Texanolisobutyrate, or a processing oil. If used in admixture, it is the totalproportion of plasticizer that is advantageously within the ranges givenabove.

The plasticized polymeric compositions of the invention may be made upin numerous forms and have various end-uses. For example, they may be inthe form of a dryblend, a paste, or a plastisol, depending on the gradeof the resin employed. They may be used, for example, as coatings, indipping, spraying, injection or rotational moulding, extrusion, or asself-supporting films and sheets, and may readily be foamed. End usesinclude flooring materials, wall coverings, moulded products, upholsterymaterials, leather substitutes, electrical insulation, especially wireand cable, coated fabrics, toys, and automobile parts.

The invention is illustrated by reference to the accompanying Exampleswhich illustrate the extent to which isobutylene can be converted byrhodium hydroformylation and also the hydroformylation of mixed butenefeeds one of which was prepared to represent a butene feed from anoxygenate to olefin reaction and the other a butene feed fromsteamcracking of petrochemical feedstocks followed by selectivehydrogenation of butadiene. The latter is called here raffinate 1.5 forconvenience.

EXAMPLES

The following procedure was employed in Examples 1 to 6.

Hydroformylation was carried out in a standard half litre zipperclavereactor from Autoclave Engineers. Mixing occurred with an air drivenstirrer with speed controlled at 2000 revolutions per minute. The mixerhad a six bladed impeller that guaranteed a strong mixing between thegas and the liquid phase. Baffles inside the reactor prevented vortexformation and created back mixing. The reaction temperature wascontrolled at 95° C.+/−1° C. Pressure was controlled at 10barg+/−0.1bar. Synthesis gas (48% H₂ and 52% CO) was delivered from a calibratedhigh pressure storage cylinder equipped with a pressure transmitterallowing pressure reading at 0.01 bar accuracy.

Each experiment started with a catalyst solution of the followingcomposition:

-   -   Ligand A=0.244 g    -   Tetraglyme (solvent)=191.2 g    -   Rhodium=0.011 g    -   The rhodium was dosed using rhodium carbonyl acetylacetonate as        catalyst precursor.

The catalyst solution contained 56 wtppm rhodium.

The catalyst solution was transferred into the reactor. The reactor waspurged several times with syngas to remove air. The reactor content wasthen heated up to 95° C. under 2 barg syngas pressure.

Examples 7 to 10 were performed in a similar manner usingtriphenylphosphine (TPP) as a ligand at 110° C.

Once the desired reaction temperature was reached, about 0.05 mol ofolefin was injected in the catalyst solution by means of synthesis gasand at the same time of the substrate injection the pressure wasadjusted to 10 barg. Immediately after the olefin injection and pressureadjustment, the progress of the reaction was followed by measuring therate of gas consumption, indicated by the pressure decay in the highpressure syngas storage cylinder.

The test duration was 3 hours. At the end of the reaction the gas supplywas stopped and the reactor was cooled down to room temperature. Then agas sample was taken from the gas phase inside the reactor and analysedon a HP6890 gas chromatograph equipped with a thermal conductivitydetector (TCD) detection system and a poraplot Q column of 30m length,0.53 mm internal diameter (ID), 10 micrometer film thickness (df). Aliquid sample was then withdrawn from the reactor into a cooled samplevial and analysed for product composition by gas chromatography using aHP6890 gas chromatograph equipped with a flame ionisation detector (FID)detection system and a WCOT Ultimetal column of 10 m*0.53 mm ID, 0.17micrometer df HPSimdistC. For the determination of dimethylether asecond analysis was carried out over a chrompack, CP Wax 52 fused silicaof 50 m*0.25 mm ID, 0.2 micrometer df. For the determination ofacetaldehyde a second analysis was carried out over a capillary columnHP-FFAP polyethyleneglycol TPA (terephthalic acid) of 50 m*0.32 mm ID,0.5 micrometer df.

Sulphur analyses of the products were done on a HP6890 gas chromatographequipped with a fused silica column of 30m*0.32 ID*5 micrometer CPSIL5CBand a model 355 flameless sulphur chemoluminescence detector fromSievers.

Finally the reactor was depressurized and the liquid recovered andweighed. From the weight of the product, its composition and thecomposition of the off-gas, a substrate molar end-conversion wascalculated. The conversion at any given moment could be calculatedpro-rata the pressure drop at that moment, the measured end-conversionand the total pressure drop achieved at the end of the experiment.

The results obtained were as follows.

Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 Feed (grams) i-butene4.600 0.968 0.180 0.164 2.7 n-butene-1 4.600 1.804 1.215 1.107 2.7 2.7n-butene-2 4.3 1.408 2.655 2.419 2.7 n-butane 0.176 0.360 0.328 i-butane0.044 0.090 0.082 Ligand A 0.244 0.244 0.244 0.244 0.244 0.244 TPP 19.8419.84 19.84 19.54 Rhodium 0.011 0.011 0.011 0.011 0.011 0.011 0.005760.00576 0.00576 0.00576 Tetraglyme 191.2 191.2 191.2 191.2 191.2 191.2191.2 191.2 191.2 191.2 Product (grams) C4 1.271 0.528 0.722 0.824 0.1240.127 2.24 1.97 3Me butyraldehyde 1.109 0.041 0.052 0.45 2Mebutyraldehyde 0.306 0.695 0.356 0.114 0.206 0.663 0.717 0.59n-valeraldehyde 5.773 4.524 0.519 3.867 3.644 3.813 3.314 3.503 0.130.17 Ligand 0.420 0.104 0.168 0.415 0.214 0.227 Valeric acid 0.000 0.0000.000 0.000 0.000 0.000 0.041 0.042 0.00 0.00 Tetraglyme 189.089 189.078188.274 189.204 189.239 187.931 180.985 183.929 186.16 188.62 C4 inoffgas 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.29 0.45

The results show that

Example 1 n-butene-1 Hydroformylation

The conversion was 86%.

Example 2 n-butene-2 (40% cis and 60% trans) Hydroformylation

The conversion was 79%.

Example 3 Iso-Butylene Hydroformylation

The conversion was 81.7%. It is believed that the trace ofn-valeraldehyde in the product originated from a feed impurity.

Example 4 Raffinate 1.5 Hydroformylation

The mixture that was used had following composition by weightedblending:

-   -   22 wt % isobutylene, 41 wt % n-butene-1, 32 wt % mixed        n-butene-2s (cis and trans), 4 wt % n-butane and 1 wt %        isobutane

The end conversion was 82.9%. The relative break-down of the aldehydeswas 20.8% 3-methylbutanal, 6.7% 2-methylbutanal and 72.1%n-valeraldehyde. Based on molar balance the isobutene showed to havereached 74.5% conversion. The cumulative conversion of n-butene-1 andn-butene-2s was 84.5%. There was no evidence by GC of the presence ofany pivaldehyde or 2,2-dimethyl propanal.

Example 5 Hydroformylation of Oxygenate to Olefin Based Mixed Butenes

The mixture that was used was obtained by mixing to represent a butenestream that would be obtained from the conversion of methanol toolefins, and had the following composition by weighed blending:

-   -   4 wt % isobutene, 27 wt % n-butene-1, 59 wt % mixed n-butene-2s        (cis and trans), 8 wt % n-butane, 2 wt % isobutane.

The overall conversion was 67%. The relative break-down of the aldehydeswas 3.98% 3-methylbutanal, 2.92% 2-methylbutanal and 93.1%n-valeraldehyde. Based on a molar balance, the isobutene showed to havereached 61.8% conversion. The cumulative conversion of n-butene-1 andn-butene-2s was 69.3%. There was no evidence by GC of the presence ofany pivaldehyde or 2,2-dimethyl propanal.

Example 6 Hydroformylation of Oxygenate to Olefin Based Mixed Buteneswith Acetaldehyde

In this experiment 0.5 wt % of acetaldehyde (1 gram) was injected in thecatalyst solution to give a molar ratio of acetaldehyde to rhodium of211.

A first order reaction rate constant of 0.51 h⁻¹ was measured,indicating no decrease in reaction rate compared to the base case ofExample 5, where the first order reaction rate constant as measured was0.47 h⁻¹.

The results indicate that acetaldehyde has no inhibiting effect on thehydroformylation rate of mixed butenes in the low pressurerhodium/Ligand A system.

GC analysis of the final products showed 0.47 wt % of acetaldehyde(0.917 gram), indicating that acetaldehyde essentially did not take partin any reaction.

Examples 7 and 8 Butene-1 Hydroformylation

Two experiments were carried out to provide a base case reaction ratefor n-butene-1 hydroformylation with rhodium and triphenyl phosphine ascatalyst. The two runs also provided indication about thereproducibility of the experiments.

Examples 9 and 10 Butene-2 and Iso-Butylene Hydroformylation

N-butene-2s and isobutene was also tested as substrates inhydroformylation with rhodium and triphenylposphine. Both substratesshowed at 110° C. and 10 barg a reaction rate of about 0.05 h⁻¹ andreacted therefore about 50 times slower than n-butene-1. The mainproduct components are branched valeraldehydes, while only very littlen-valeraldehyde is produced.

These results show that butene-1 will always react quickly and that byselecting the appropriate conditions (temperature, carbon monoxidepartial pressure and residence time), butene-2s and isobutylene can alsobe made to react, as is illustrated in FIG. 1 which plots theconversions over time achieved in Examples 1, 2 and 3.

1.-23. (canceled)
 24. A C₅ aldehyde mixture comprising n-pentanal,3-methyl-butanal and 2-methyl-butanal wherein i. the ratio of n-pentanalto 2-methyl-butanal is from 3:1 to 100:1; and ii. the ratio of3-methyl-butanal to 2-methyl-butanal is at least 0.3:1, and comprisingfrom 50 wt % to 75 wt % of n-pentanal.
 25. The C₅ aldehyde mixtureaccording to claim 24, further comprising at least 20 wt %3-methyl-butanal.
 26. A C₅ aldehyde mixture comprising n-pentanal,3-methyl-butanal and 2-methyl-butanal wherein i. the ratio of n-pentanalto 2-methyl-butanal is from 3:1 to 100:1; and ii. the ratio of3-methyl-butanal to 2-methyl-butanal is at least 0.3:1, and comprisingat least 20 wt % 3-methyl-butanal.
 27. A C₅ alcohol mixture consistingessentially of normal and mono-methyl branched alcohols and comprisingn-pentanol, 2-methyl-butanol and 3-methyl-butanol wherein i. n-pentanoland 2-methyl-butanol are present in a ratio from 3:1 to 100:1; and ii.3-methyl-butanol and 2-methyl-butanol are present in a ratio of at least0.3:1, and comprising from 50 wt % to 75 wt % of n-pentanol.
 28. Anester of an alcohol mixture according to claim
 27. 29. An ester of analcohol mixture according to claim 27 comprising a diester.
 30. An esterof an alcohol mixture according to claim 27 comprising a phthalateester.
 31. A C₅ acid mixture consisting essentially of normal andmono-methyl branched acids and comprising n-pentanoic acid,2-methyl-butanoic acid and 3-methyl-butanoic acid wherein i. n-pentanoicacid and 2-methyl-butanoic acid are present in a ratio from 3:1 to100:1; and ii. 3-methyl-butanoic acid and 2-methyl-butanoic acid arepresent in a ratio of at least 0.3:1, and comprising from 50 wt % to 75wt % of n-pentanoic acid.
 32. An ester of an acid mixture according toclaim
 31. 33. An ester of an acid mixture according to claim 31comprising an ester of a polyol.
 34. An aldehyde mixture comprising:2-isopropyl-2-heptenal; 2-propyl-2-heptenal;2-propyl-5-methyl-2-hexenal; 2-propyl-4-methyl-2-hexenal and2-isopropyl-4-methyl-2-hexenal comprising at least 20 wt %2-propyl-2-heptenal and wherein the ratio of the combined amount of2-isopropyl-2-heptenal and 2-propyl-5-methyl-2-hexenal to the combinedamount of 2-propyl-4-methyl-2-hexenal and 2-isopropyl-4-methyl-2-hexenalis at least 0.3.
 35. An aldehyde mixture comprising: 2-isopropylheptanal; 2-propyl heptanal; 2-propyl-5-methyl hexanal;2-propyl-4-methyl hexanal and 2-isopropyl-4-methyl hexanal comprising atleast 20 wt % 2-propyl heptanal and wherein the ratio of the combinedamount of 2-isopropyl heptanal and 2-propyl-5-methyl hexanal to thecombined amount of 2-propyl-4-methyl hexanal and 2-isopropyl-4-methylhexanal is at least 0.3.
 36. An alcohol mixture comprising:2-isopropyl-2-heptenol; 2-propyl-2-heptenol;2-propyl-5-methyl-2-hexenol; 2-propyl-4-methyl-2-hexenol and2-isopropyl-4-methyl-2-hexenol comprising at least 20 wt %2-propyl-2-heptenol and wherein the ratio of the combined amount of2-isopropyl-heptenol and 2-propyl-5-methyl-2-hexenol to the combinedamount of 2-propyl-4-methyl-2-hexenol and 2-isopropyl-4-methyl-2-hexenolis at least 0.3.
 37. An ester of an alcohol mixture according to claim36.
 38. An ester of an alcohol mixture according to claim 36 comprisinga diester.
 39. An ester of an alcohol mixture according to claim 36comprising a phthalate ester.
 40. An alcohol mixture comprising:2-isopropyl heptanol; 2-propyl heptanol; 2-propyl-5-methyl hexanol;2-propyl-4-methyl hexanol and 2-isopropyl-4-methyl hexanol comprising atleast 20 wt % 2-propyl heptanol and wherein the ratio of the combinedamount of 2-isopropyl heptanol and 2-propyl-5-methyl hexanol to thecombined amount of 2-propyl-4-methyl hexanol and 2-isopropyl-4-methylhexanol is at least 0.3.
 41. An ester of an alcohol mixture according toclaim
 40. 42. An ester of an alcohol mixture according to claim 40comprising a diester.
 43. An ester of an alcohol mixture according toclaim 40 comprising a phthalate ester.
 44. An acid mixture comprising:2-isopropyl heptanoic acid; 2-propyl heptanoic acid; 2-propyl-5-methylhexanoic acid; 2-propyl-4-methyl hexanoic acid and 2-isopropyl-4-methylhexanoic acid comprising at least 20 wt % 2-propyl heptanoic acid andwherein the ratio of the combined amount of 2-isopropyl heptanoic acidand 2-propyl-5-methyl hexanoic acid to the combined amount of2-propyl-4-methyl hexanoic acid and 2-isopropyl-4-methyl hexanoic acidis at least 0.3.
 45. An ester of an acid mixture according to claim 44.46. An ester of an acid mixture according to claim 44 comprising anester of a polyol.